Kohler and Milstein are generally credited with having devised the techniques that successfully resulted in the formation of the first monoclonal antibody-producing hybridomas (G. Kohler and C. Milstein, 1975, Nature 256, 495-497; 1976, Eur. J., Immunol. 6, 511-519). By fusing antibody-forming cells (spleen B-lymphocytes) with myeloma cells (malignant cells of bone marrow primary tumors) they created a hybrid cell line, arising from a single fused cell hybrid (called a hybridoma or clone). The hybridoma had inherited certain characteristics of both the lymphocytes and the myeloma cell lines. Like the lymphocytes, the hybridoma secreted a single type of immunoglobulin; moreover, like the myeloma cells, the hybridoma had the potential for indefinite cell division. The combination of these two features offered distinct advantages over conventional antisera.
Antisera derived from vaccinated animals are variable mixtures of polyclonal antibodies which never can be reproduced identically. Monoclonal antibodies are highly specific immunoglobulins of a single type. The single type of immunoglobulins secreted by a hybridoma is specific to one and only one antigenic determinant, or epitope, on the antigen, a complex molecule having a multiplicity of antigenic determinants. For instance, if the antigen is a protein, an antigenic determinant may be one of the many peptide sequences (generally 6-7 amino acids in length; M. Z. Atassi, 1980, Molec. Cell. Biochem. 32, 21-43) within the entire protein molecule. Hence, monoclonal antibodies raised against a single antigen may be distinct from each other depending on the determinant that induced their formation; but for any given hybridoma, all of the antibodies it produces are identical. Furthermore, the hybridoma cell line is easily propagated in vitro or in vivo, and yields monoclonal antibodies in extremely high concentration.
A monoclonal antibody can be utilized as a probe to detect its antigen. Thus, monoclonal antibodies have been used in in vitro diagnostics, for example, radioimmunoassays and enzyme-linked immunoassays (ELISA), and in in vivo diagnostics, e.g. in vivo imaging with a radiolabeled monoclonal antibody. Also, a monoclonal antibody can be utilized as a vehicle for drug delivery to such antibodies, antigen.
However, before a monoclonal antibody can be utilized for such purpose, it is essential that the monoclonal antibody be capable of binding to the antigen of interest; i.e., the target antigen. This procedure is carried out by screening the hybridomas that are formed to determine which hybridomas, if any, produce a monoclonal antibody that is capable of binding to the target antigen. This screening procedure can be very tedious in that numerous, for example, perhaps several thousand, monoclonal antibodies may have to be screened before a hybridoma that produces an antibody that is capable of binding the target antigen is identified. Accordingly, there is the need for a method for the production of monoclonal antibodies that increases the likelihood that the hybridoma will produce an antibody to the target antigen.